Process of making a contact transfer printing surface by complementary light



Patented June l5, 1926.

UNITED STATESI PATENT OFFICE.

ROBERT JOHN, OF NEW YORK, N. Y., ASSIGNOB TO DAYLIGHT FILI CORPORATION, A

` CORPORATION OF NEW YORK.

PROCESS OF IAXING A CONTACT TRANSFER PRINTING SURFACE BY COHPLE- HENTABY LIGHT'.

Application led July 25, 1919. Serial lo. 313,240.

My invention relates to a process of making a contact transfer printing surfaceby complementary light and has for its object to produce a printing surface which 1s mounted on a suitable carrier and which represents photographic lights and shades in such a manner that copies may be made therefrom by a dye or ink transfer contact process.

In order to enable the invention more readily to be understood, reference is made to the accompanying drawings in which Fig. 1 illustrates a method of practicing the invention in connection with an arc lamp and Fig. 2 illustrates a method of practicing the invention in. connection with a mercury vapor lamp.

In these drawings the numeral 1 designates the carbons of an arc lamp between which an arc is formed, the arc emitting rays of the light 2 which pass through an absorption lter 3 having a coating 4, whence the rays of complementary light 5 pass through the negative 6 and strike the sensitized plate 7 comprising a transparent carrier having thereon a sensitized emulsion 8. Referring particularlyto Fig. 2 the numeral 9 designates a mercury vapor lamp emitting light rays 10 which pass through an absorption filter 11 having a coating 12, whence the rays of complementary light pass through the negative 14 and strike the sensitized plate 15 comprising a transparent carrier having thereon a sensitized emulsion 16.

For purposes of illustration, my invention will be described in connection with the formation of a printing surface. obtained by exposing to the action of light modified by the lights and shades of a completed negative which it is desired to reproduce, a sensitized emulsion mounted on a transparent carrier through which it preferably is exposed, whichthen is treated to form a hardened printing surface. If it is desired that the printing surface consist of granules or great numbers of photographically formed, extremely minute, individual protuberances which are distributed and grouped irregularly so as to represent photographic lights and shades, it may be obtained, for example, by treating the emulsion in the manner set forth in my copending application Serial No. 313,237, filed July 25, 1919, for process of photogra hic reproduction, which eventuated into atent No. 1,374,853, granted April 12, 1921, for process of photographic reproduction.

It is considered desirable in producing a printing surface to expose the sensitized emulsion through its transparent carrier rather than on its outside surface in order that the printing surface may be as close as possible to the carrier. If the emulsion is exposed on its outside surface, it is necessary to strip the emulsion from its carrier in order to remove the unhardened portions which will lie adjacent the carrier. Stripping the emulsion is a delicate operation which can be performed only by those skilled in the art and is likely to injure the image.

lVhen an emulsion is exposed through its transparent carrier, however, certain diiculties are encountered in the formation of the printing surface. In the first lace, the treating solution must penetrate tie entire emulsion in order to reach the light affected portions adjacent the transparent carrier. This usually is accomplished by the use of an excess of alkali, such, for example, as sodium carbonate, which opens the pores of the emulsion and carries the solution through. The objection to this is that the excess of alkali has a tendency to affect the image unfavorably, destroy the delicate intcrmediate shades, and make it too contrasting. In the second place, an ordinary sensitized emulsion usually is in excess of onethousandth of an inch in thickness, while the preferable printing surface adjacent the carrier should be very thin, substantially one ten-thousandth of an inch or less. As this thick emulsion will be penetrated deeply by the light to which it is exposed, particularly that portion of the light coming through clear spaces or light shadows in the negative which is being reproduced, the resultant printing surface after treatment will give a relatively too thick printing surface 1n those portions. This undesirable thickness is increased by the use of an alkali as referred to above. It is very difficult, therefore, to get the darker portions of the negative recorded properly without having the lighter portions of the negative registered too heavy and deep.

One manner of overcoming the above difa slightly greenish yellow, such being iiculties has been to incorporate in the emulsion a liglit-restraining agent such as tartrazine or a chrome yellow pigment which has the property of absorbing or slowing down the action oi the printingr rays sufli ciently to enable. the dark portions of the negative which being reproduced to be registered on the sensitized particles in the emusion adjacent the carrier, before the prnling rays coming through light portions of the negative have penetrated the emulsion so deeply as to form a printing surface which is too'thick in the portions corresponding to said light portions of the negative, after the printing surface has been treated and the portions of emulsion unaffected by light removed. The use of these light-restraining agents, however, has disadvantages, amon which may be mentioned their deterring e. ect on the sensitized emulsion so that a longer time of exposure is required. Although this additional time of.

exposure is not a serious handicap in plate photography, it is important in motion pleture photography where the speed of running the large number of individual pictures'upon a motion picture film through the printer is a material factor.

In order to overcome these disadvantages, I have discovered that excellent results may be obtained by the use of a printing light complementary in color to the natural color of the sensitized emulsion, inwhich, in the embodiment of my invention chosen for pur-Y poses of illustration, may be described as pf t e natural color of the ordinary gelatinous silver bromide emulsion. Such a printing light can be found, for example, in the highest visible violet rays of the spectrum.

It an ordinary sensitized emulsion of any desired thickness is exposed to'such a printing light modiied by any desired'lights and shades as, for instance, those of a negative which it is desired to reproduce, the printing light which comes through the highlights of the negative will be absorbed or slowed down to such an extent that the printing light Which comes through-the dark shades of the negative will be recorded in the sensitized emulsion Without a too deep penetration of the printing light coming through said high lights of the negative.` If the sensitized emulsion is exposed through its transparent carrier, the entire printing surface obtained after treat-ment will lie adjacent the carrier, which is desirable to preventa too great thickness of printing surface corresponding to the high lights of the negative, the effect of which excessivel thickness is to cause the lights and shades to be too contrasting.

Lights complementary to the slightly greenish yellow of the sensitized emulsion may be obtained in any desired manner. An

are lamp using what is known as blue flame carbons, or a mercury vapor lamp, Will give satisfactory results, if absorption, filters are used to stop undesirable printing rays such, for example, as blue rays andviolet rays above the higher visible rays. Glass coated with a solution of methyl violet in gelatin may be used as a filter. Although such a filter is sulicient with a printing light obtained from an are of blue flame carbons, it is desirable with a mercury vapor light to make the filter of glass thick enough to absorb the ultra violet and the higher invisible rays.

Many modifications of my invention will be apparent to those skilled in the art without departing therefrom or from the scope of the claims, my invention not being limited to any particular emulsion or to any particular light but comprising the use of a printing. light complementary to the natural color of the emulsion.

What I claim is:

l.. The process of photographic printing which consists in exposing the sensitized emulsion on which the print is to be made to a photographic printing light which is complementary in color to the natural color of said sensitized emulsion in order to limit the penetration of the printing rays in the emuls1on. t

Q The process of photographie printing which consists in exposing through its transparent carrier the sensitized emulsion on Which the print is to be made to a photographic printing light which is complementary in color to the natural color of said sensitized emulsion in order to limit the penetration of the printing rays in the emulsion.

3. The process of photographic printingr which consists in exposing the sensitized emulsion on which the print is to be made to a photographic printing light which is complementary in color to the natural sllghtly greenish yellow color of said sensitized emulsion in order to limit the penetration of the printing rays in the emulsion.

4. The process of photographic printing which consists in exposing the sensitized emulsion on which the print is to be made to a photographic printing light from which blue photographic rays are substantially absent in order to limit the penetration of the printing rays in the emulsion.

5. The process of photographic. printing which consists in exposing the sensitized emulsion on whic'h the print is to be made to a photographic printing light containing violet photographic rays and from which blue photographic rays are substantially absent in order to limit the penetration of the printing rays in the emulsion.`

6. The process of photographic printing which consists in exposing the sensitized emulsion on which the print is tobe made to a photographic printing light produced by a mercury vapor light and passed through a screen Which eliminates practically all photographic printing rays except middle violet photographic rays in order to limit the penetration of the printing rays in the emulsion.

7. The process of photographic printing which consists in exposing through its transparent carrier the sensitized emulsion on which the print is to be made to a photographic printing light produced by a mercury vapor light and passed throu h a screen which eliminates practically all p otographic printing rays except middle Violet photographic rays in order to limit the penetration of the printing rays in the emulsion.

8. The process of producing in a sensitized emulsion, photographic changes corresponding to the lights and shades of a photographic record, which consists in exposing said emulsion to an actinic light modified by the lights and shades of said record and which is complementary in color to 'the natural color of said emulsion in order to limit the penetration of the printing rays in the emulsion.

9. The process of producing in a sensitized emulsion, photographic changes corresponding to the lights and shades of a photographic record, which consists in exposing said emulsion through its transparent carrier to an actinic light modified by the lights and shades of said record and which iscomplementary in color to the natural color of said emulsion in order to limit the penetration of the printing rays in the emulsion.

10. The process of producing in a sensitized emulsion, photographic changes correspondin to the lights and shades of a photograp ic record, which consistsv in exposin said emulsion to an actinic light modified by the lights and shades of said record and which is complementar A in color to the natural slightly reenish yellow color of said emulsion 1n o er to limitv the enetration of the printing rays in the emu sion.

l1. The rocess of producing in a sensitized emulsion, photographic changes corresponding to the lights and shades of a photographic record, which consists in exposing said emulsion through its transparent carrier to an actinic light modified by the lights and .shades of said record and which is complementary in color to the natural slightly greenish ellow color of said emulsion in order tov imit the penetration of the printing rays in the emulsion.

12. The process of vproducing in a sensi- 4tized emulsion, photographic changes corresponding to the lights and shades of a photographic record, which consists in exposing said emulsion to an actinic light modified by the lights and shades of said record and which vconsists of violet actinic rays fromv which substantially all blue actinic rays have been eliminated in order to limit the penetration of the printing rays in the emulsion.

13. The process of producing in a sensitized emulsion, photographic changes corresponding to the lights and shades of a photographic record, which consists in exposing said emulsion to an actinic light modilied by the lights and shades of said record and produced by a mercury vapor lamp and passed through a screen which eliminates practically all actinic rays except middle violet actinic rays in order to limit the penetration of the printing rays in the emulsion.

14. The process of producing in a sensitized emulsion, photographic changes corresponding to the lights and shades of a photographic record, which consists in exposing said emulsion through its transparent carrier to an actinic light modified by the lights and shades of said record and produced by a mercury vapor lamp and passed through a screen which eliminates practically all actinic rays except middle violet actinic rays in order to limit the penetration of the printing rays in the emulsion.

15. The process of producing in a sensitized emulsion, photographic changes corresponding to the lights and shades of a photographic record, which consists in exposing vsaid emulsion to an actinic li ht modified posing said emulsion through its transparent carrier to an actinic light modified by the lights and shades of said record and produced by a mercury vapor lamp and passed through a screen which eliminates practically all the higher and lower actinic rays in order to limit the penetration of the printing rays in the emulsion.

In testimony that I claim the fore oing, I have hereunto set my hand this 23x' day of July, 1919.

ROBERT JOHN. 

